Module 5 - Aqueous Solutions
What is the formula for Molarity?
mol/L = [M]
What will an acid-base reaction always produce?
Salt and water!
What does STP mean and what are the values?
Standard Temperature Pressure!
273.15 K and 1 atm
1 L * atm is equal to how many Joules?
101.325 Joules
If a chemical reaction has a negative change in enthalpy (-ΔH), is the reaction endothermic or exothermic?
Exothermic - heat is released to the surroundings
Is Calcium Nitrate soluble or insoluble in water?
Soluble!
What is the oxidation number of oxygen in most compounds such as H2O or CO2?
-2
If the volume of a gas is halved while the temperature remains constant, what happens to the pressure? What law is this?
It doubles - Boyle's Law
A mechanical piston compresses a sample of neon gas from 1.20 L to 0.450 L under a constant external pressure of 3.50 atm.
a) Calculate the work done by the gas in Joules.
b) is work being done BY or ON the system?
+266.0
Work is done ON the system.
Does the process of sublimation (solid to gas) have a positive or negative enthalpy change?
+ΔH; it is an endothermic process where energy must be absorbed to break intermolecular forces.
Suppose you have 455 grams of glucose (C6H12O6) dissolved in 750.0 mL of water. What is the molarity of this solution?
3.37 M
A solution containing 30.0 mL of HCl at an unknown concentration is neutralized to find that a total of 52.0 mL of a 1.10 M of NaOH is required to reach the equivalence point for this reaction. What is concentration of the unknown solution?
1.91 M of HCl concentration
What is the volume (in Liters) occupied by 1.00 mole of an ideal gas at STP?
22.4 L
How much heat is required to raise the temperature of 50.0 g of water from 25.0°C to 45.0°C. (Hint: What is the specific heat of water?)
4,184 J
What is the standard enthalpy of formation (ΔHf°) for any element in its most stable form?
0 kJ/mol
Give me an example of a strong acid and strong base. (CSI NBCC)
Strong Acids: Nitric Acid, Sulfuric Acid, Perchloric Acid, Chloric Acid, Hydrochloric Acid, Hydrobromic Acid, Hydroiodic Acid.
Strong Bases: Sodium Hydroxide, Lithium Hydroxide, Cesium Hydroxide, Potassium Hydroxide, Potassium Hydroxide, Rubidium Hydroxide, Barium Hydroxide, Strontium Hydroxide.
Determine the oxidation state of Manganese in the permanganate ion (MnO4-)?
+7
A balloon has a volume of 2.0 L at 298 K. If the temperature is increased to 350 K at a constant pressure, what is the new volume?
2.35 L
A 25.0 g sample of an unknown metal absorbs 435 J of heat. This energy causes the temperature of the metal to rise by 20.0 °C. What is the specific heat capacity of the metal?
0.87 J/g°C
Calculate the standard enthalpy change (ΔHrxn) for the combustion of methane (CH4) using the following data:
CH4 (g) (ΔHf) = -74.8 kJ/mol
CO2 (g) (ΔHf) = -393.5 kJ/mol
H2O (l) (ΔHf) = -285.8 kJ/mol
-890.3 kJ/mol
Write the BALANCED, and NET IONIC equation for the reaction between aqueous potassium carbonate and aqueous calcium chloride. (Use your solubility rules to determine which products forms a precipitate)
Ca2+(aq) + CO32- -> CaCO3(s)
In the reaction Zn (s) + 2HCl (aq) -> ZnCl2 (aq) + H2 (g), which element is being oxidized? Which is the oxidizing agent?
Zinc (Zn) is oxidized as it increases from 0 to +2. The oxidizing agent is H2 as it reducing which is the oxidizing agent.
A mixture of Helium and Neon has a total pressure of 1.2 atm. If the partial pressure of the Helium is 0.4 atm, what is the mole fraction of Neon in the mixture?
2/3 or 0.67
A 150.0 g block of copper (specific heat = 0.385 J/g°C) is heated to 95.00°C. It is then placed into an insulated carafe containing 1.00 L (1000 g) of water at 22.00°C.
Find the final temperature of the system once it reached equilibrium.
Tf = 22.99°C
*Notice how the temperature of the water barely moved (less than 1 degree), while the copper dropped significantly. The high specific heat of water allows it to absorb a lot of energy with minimal temperature change!
Calculate ΔH for the reaction A -> C ΔH = ???
Given:
A -> B ΔH = +100 kJ
C -> B ΔH = +150 kJ
ΔHrxn = -50 kJ